Functional evaluation of a fluorescent schweinfurthin: mechanism of cytotoxicity and intracellular quantification

Craig H Kuder; Ryan M Sheehy; Jeffrey D Neighbors; David F Wiemer; Raymond J Hohl

doi:10.1124/mol.111.077107

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Functional evaluation of a fluorescent schweinfurthin: mechanism of cytotoxicity and intracellular quantification

Journal article

Open access

Peer reviewed

Functional evaluation of a fluorescent schweinfurthin: mechanism of cytotoxicity and intracellular quantification

Craig H Kuder, Ryan M Sheehy, Jeffrey D Neighbors, David F Wiemer and Raymond J Hohl

Molecular pharmacology, Vol.82(1), pp.9-16

07/2012

DOI: 10.1124/mol.111.077107

PMCID: PMC3382832

PMID: 22461663

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Abstract

Schweinfurthins are potent inhibitors of cancer cell growth, especially against human central nervous system tumor lines such as SF-295 cells. However, the mechanisms through which these compounds impede cell growth are not fully understood. In an effort to understand the basis for the effects of schweinfurthins, we present a fluorescent schweinfurthin, 3-deoxyschweinfurthin B-like p-nitro-bis-stilbene (3dSB-PNBS), which displays biological activity similar to that of 3-deoxyschweinfurthin B (3dSB). These two schweinfurthins retain the unique differential activity of the natural schweinfurthins, as evidenced by the spindle-like morphological changes induced in SF-295 cells and the unaltered appearance of human lung carcinoma A549 cells. We demonstrate that incubation with 3dSB or 3dSB-PNBS results in cleavage of poly-ADP-ribose polymerase (PARP) and caspase-9, both markers of apoptosis. Coincubation of 3dSB or 3dSB-PNBS with the caspase-9 inhibitor (Z)-Leu-Glu(O-methyl)-His-Asp(O-methyl)-fluoromethylketone prevents PARP cleavage. Therapeutic agents that induce apoptosis often activate cellular stress pathways. A marker for multiple stress pathways is the phosphorylation of eukaryotic initiation factor 2α, which is phosphorylated in response to 3dSB and 3dSB-PNBS treatment. Glucose-regulated protein 78 and protein disulfide isomerase, both endoplasmic reticulum chaperones, are up-regulated with schweinfurthin exposure. Using the fluorescent properties of 3dSB-PNBS and dimethoxyphenyl-p-nitro-bis-stilbene (DMP-PNBS), a control compound, we show that the intracellular levels of 3dSB-PNBS are higher than those of Rhodamine 123 or DMP-PNBS in SF-295 and A549 cells.

Caspase 9 - metabolism

Apoptosis - drug effects

Protein Disulfide-Isomerases - metabolism

Heat-Shock Proteins - metabolism

Humans

Endoplasmic Reticulum - metabolism

Stilbenes - pharmacology

HSP70 Heat-Shock Proteins - metabolism

Up-Regulation - drug effects

Poly(ADP-ribose) Polymerases - metabolism

Endoplasmic Reticulum - drug effects

Glioblastoma - pathology

Cell Line, Tumor

Eukaryotic Initiation Factor-2 - metabolism

Fluorescent Dyes - pharmacology

Membrane Proteins - metabolism

Phosphorylation - drug effects

Glioblastoma - drug therapy

Details

Title: Subtitle: Functional evaluation of a fluorescent schweinfurthin: mechanism of cytotoxicity and intracellular quantification
Creators: Craig H Kuder - Department of Internal Medicine, University of Iowa, Iowa City, Iowa 52242, USA
Ryan M Sheehy
Jeffrey D Neighbors
David F Wiemer
Raymond J Hohl
Resource Type: Journal article
Publication Details: Molecular pharmacology, Vol.82(1), pp.9-16
Publisher: United States
DOI: 10.1124/mol.111.077107
PMID: 22461663
PMCID: PMC3382832
ISSN: 1521-0111
eISSN: 1521-0111
Grant note: R41 CA126020 / NCI NIH HHS T32 CA078586 / NCI NIH HHS 1R41-CA126020-01 / NCI NIH HHS
Language: English
Date published: 07/2012
Academic Unit: Neuroscience and Pharmacology; Chemistry; Internal Medicine
Record Identifier: 9983985961102771

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